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Effect of pairing correlation on the low-lying quadrupole states in sn isotopes
Shuai Sun, Shi-Sheng Zhang, Zhen-Hua Zhang, Li-Gang Cao
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Abstract:
The low-lying quadrupole states in Sn isotopes have been investigated in the framework of fully self-consistent Hartree-Fock+BCS plus QRPA. We pay attention to how the density-dependence of pairing interaction affects the properties of low-lying quadrupole state. The SLy5 Skyrme interaction with surface, mixed, and volume pairings are employed in the calculations, respectively. We find that the excitation energies and the corresponding reduced electric transition probabilities of first 2+ state are different given by three pairing interactions. The properties of quasiparticle state, two-quasiparticle excitation energy, the reduced transition amplitude, and the transition densities in 112Sn are analyzed in details. Two different mechanisms, static and dynamical effect, of pairing correlation are also discussed. The results show that the surface, mixed, and volume pairing indeed affect the properties of first 2+ state in Sn isotopes.
Search for dark matter production in association with the Z' boson at the LHC in pp collisions at $ \sqrt{s} $ = 8 TeV using Monte Carlo simulations
S. Elgammal, M. A. Louka, A. Y. Ellithi, M. T. Hussein
Published:   , doi: 10.1088/1674-1137/ac061c
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This analysis presents the possibility for the search for Dark Matter (DM) particles using events with a Z\begin{document}$ ^{\prime} $\end{document} heavy gauge boson and a large missing transverse momentum at the Large Hadron Collider (LHC). We consider the muonic decay of Z\begin{document}$ ^{\prime} $\end{document}. The analyzed Monte Carlo samples were the Open simulated files produced by the Compact Muon Solenoid (CMS) collaboration for proton-proton collisions correspond to an integrated luminosity of the LHC run-I with 19.7 fb\begin{document}$ ^{-1} $\end{document} at \begin{document}$ \sqrt{s} = $\end{document} 8 TeV. Two scenarios, one simplified benchmark scenario so called Dark Higgs and the effective field theory (EFT) formalism, were used for interpretations. Limits are set on both Z\begin{document}$ ^{\prime} $\end{document}, dark matter masses and the cutoff scale of the EFT.
Dark matter, Z′, vector-like quark at the LHC and bsμμ anomaly
Wei Chao, Hong-Xin Wang, Lei Wang, Yang Zhang
Published:   , doi: 10.1088/1674-1137/ac06ba
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Combining the \begin{document}$ b\to s\mu^+\mu^- $\end{document} anomaly and dark matter observables, we study the capability of LHC to test dark matter, \begin{document}$ Z^{\prime} $\end{document}, and vector-like quark. We focus on a local \begin{document}$ U(1)_{L_\mu-L_\tau} $\end{document} model with a vector-like \begin{document}$ SU(2)_L $\end{document} doublet quark Q and a complex singlet scalar whose lightest component \begin{document}$ X_I $\end{document} is a candidate of dark matter. After imposing relevant constraints, we find that the \begin{document}$ b\to s\mu^+\mu^- $\end{document} anomaly and the relic abundance of dark matter favor \begin{document}$ m_{X_I}< 350 $\end{document} GeV and \begin{document}$ m_{Z^{\prime}}< 450 $\end{document} GeV for \begin{document}$ m_Q< $\end{document} 2 TeV and \begin{document}$ m_{X_R}< $\end{document} 2 TeV (the heavy partner of \begin{document}$ m_{X_I} $\end{document}). The current searches for jets and missing transverse momentum at the LHC sizably reduce the mass ranges of the vector-like quark, and \begin{document}$ m_Q $\end{document} is required to be larger than 1.7 TeV. Finally, we discuss the possibility of probing these new particles at the high luminosity LHC via the QCD process \begin{document}$ pp \to D\bar{D} $\end{document} followed by one \begin{document}$ D\to s (b) X_I $\end{document} and the other \begin{document}$ D\to s (b) Z'X_I $\end{document} and then \begin{document}$ Z'\to $\end{document}\begin{document}$ \mu^+\mu^- $\end{document}. Taking a benchmark point of \begin{document}$ m_Q $\end{document} = 1.93 TeV, \begin{document}$ m_{Z^\prime} = 170 $\end{document} GeV, and \begin{document}$ m_{X_I} = $\end{document} 145 GeV, we perform a detailed Monte Carlo simulation, and find that such benchmark point can be accessible at the 14 TeV LHC with an integrated luminosity 3000 fb\begin{document}$ ^{-1} $\end{document}.
Influence of quantum correction on the black hole shadows, photon rings and lensing rings
Jun Peng, Minyong Guo, Xing-Hui Feng
Published:   , doi: 10.1088/1674-1137/ac06bb
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We calculate the photon sphere \begin{document}$r_{ph}$\end{document} and critical curve \begin{document}$b_c$\end{document} for the quantum corrected Schwarzschild black hole, finding that they violate universal inequalities proved for asymptotically flat black holes which satisfy null energy condition in the framework of Einstein gravity. This violation seems to be a common phenomenon when considering quantum modification of Einstein gravity. Furthermore, we study the shadows, lensing rings and photon rings in the quantum corrected Schwarzschild black hole. The violation leads to a larger bright lensing ring in the observational appearance of thin disk emission near the black hole compared with the classical Schwarzschild black hole. Our analysis may provide observational evidence for the quantum effect of general relativity.
Direct measurement of the resonance strengths and branching ratios for the low-energy (p, γ) reactions on Mg isotopes
Hao ZHANG, Zhi-Hong LI, Jun SU, Yun-Ju LI, Chen CHEN, Long ZHANG, Fu-Qiang CAO, Yang-Ping SHEN, Wei NAN, Wei-Ke NAN, Xin-Yue LI, Li-Hua CHEN, Gang LIAN, Bao-Qun CUI, Bing GUO, Wei-Ping LIU
Published:   , doi: 10.1088/1674-1137/ac06aa
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Proton capture reactions on Mg isotopes play important roles in the Mg-Al cycle in stellar H-burning. In particular, the resonance strengths and branching ratios of low-energy resonances in 25Mg(\begin{document}$ p,\gamma$\end{document})26Al reaction determine the production of 26Al, which is one of the most important long-lived radioactive nuclei in nuclear astrophysics. In the present article, we report our first experiment using the intense proton beam of about 2 mA provided by the JUNA accelerator at ground laboratory, and a new technique that can minimize the composition change of the target under the intense beam irradiation. The resonance strengths and branching ratios of E = 214, 304 and 326 keV resonances in the reactions of 24Mg(\begin{document}$ p,\gamma$\end{document})25Al, 25Mg(\begin{document}$ p,\gamma$\end{document})26Al and 26Mg(\begin{document}$ p,\gamma$\end{document})27Al were measured with a high accuracy. The success of the current experiment lays a good calibration for the nuclear astrophysical experiment at Jinping underground laboratory.
Study of the C parity violating and strangeness changing J/ψPP weak decays
Yueling Yang, Junliang Lu, Mingfei Duan, Jinshu Huang, Junfeng Sun
Published:   , doi: 10.1088/1674-1137/ac06ac
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The \begin{document}$ J/{\psi} $\end{document} weak decays are rare but possible within the standard model of elementary particles. Inspired by the potential prospects at the future intensity frontier, the C parity violating \begin{document}$ J/{\psi} $\end{document} \begin{document}$ {\to} $\end{document} \begin{document}$ {\pi}{\eta}^{({\prime})} $\end{document}, \begin{document}$ {\eta}{\eta}^{\prime} $\end{document} decays and the strangeness changing \begin{document}$ J/{\psi} $\end{document} \begin{document}$ {\to} $\end{document} \begin{document}$ {\pi}K $\end{document}, \begin{document}$ K{\eta}^{({\prime})} $\end{document} decays are studied with the perturbative QCD approach. It is found that the \begin{document}$ J/{\psi} $\end{document} \begin{document}$ {\to} $\end{document} \begin{document}$ {\eta}{\eta}^{\prime} $\end{document} decays have relatively large branching ratios, about the order of \begin{document}$ 10^{-11} $\end{document}, which might be within the measurement capability and sensitivity of the future STCF experiment.
Odd-even staggering for production cross sections of nuclei near the neutron drip-line
Bo Mei
Published:   , doi: 10.1088/1674-1137/ac06ab
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In our previous studies [Phys. Rev. C 97, 044619 (2018); Phys. Rev. C 103, 044610 (2021)], a universal odd-even staggering (OES) has been observed in extensive cross sections of isotopes not far from stability measured in different fragmentation and spallation reactions, and four OES relations have been proposed on the basis of this OES universality. However, it is still unclear whether this OES universality and OES relations are applicable for many isotopes near the drip-lines. In this work, the OES in recent experimental cross sections of very neutron-rich nuclei approaching the drip-line (from \begin{document}$^{76}$\end{document}Ge,\begin{document}$^{82}$\end{document}Se+\begin{document}$^{9}$\end{document}Be) is quantitatively investigated to validate the OES universality and OES relations further. The OES magnitudes in these experimental data approaching the neutron drip-line generally agree with those evaluated mainly from experimental data near stability in our previous studies. New OES evaluations derived from these experimental data are also recommended for more exotic nuclei near the neutron drip-line, which extends our previous OES studies. Additionally, OES relation calculations are consistent with these experimental data of very neutron-rich nuclides according to their comparisons in this work. At last, comparisons with extra experimental data (from \begin{document}$^{238}$\end{document}U+\begin{document}$^{9}$\end{document}Be) also support that new OES evaluations and OES relation calculations can be applied for exotic nuclei near the neutron drip-line.
Light fragment and neutron emission in high-energy proton induced spallation reactions
Hui-Gan Cheng, Zhao-Qing Feng
Published:   , doi: 10.1088/1674-1137/ac05a1
Abstract:
The dynamics of high-energy proton-induced spallation reactions on target nuclides of 56Fe, 58Ni, 107Ag, 112Cd, 184W, 181Ta, 197Au and 208Pb, are investigated with the quantum molecular dynamics transport model motivated by the China initiative Accelerator Driven System (CiADS) in Huizhou and China Spallation Neutron Source (CSNS) in Dongguan. The production mechanism of light nuclides and fission fragments is thoroughly analyzed and the results obtained thereby are compared with available experimental data. The statistical code GEMINI is employed in conjunction to the transport model for describing the decay of primary fragments. For the treatment of cluster emission during the preequilibrium stage, a surface coalescence model is implemented into the model. It is found that the available data in terms of total fragment yields are well reproduced in the combined approach for spallation reactions both on the heavy and light targets. The energetic light nuclides (deuteron, triton, helium isotopes etc) mainly created during the preequilibrium stage are treated within the framework of surface coalescence whereas their evaporation is described in the conventional manner by the GEMINI code. With the combined approach, a fairly well overall description of light clusters and neutron emission is obtained and some discrepancies against the experimental data are discussed. Possible production of radioactive isotopes with the spallation reactions is also analyzed, i.e., the 6,8He energy spectra.
New evidences for the σ-bond linear-chain molecular structure in 14C
Han-zhou Yu, Jing Li, Yan-Lin Ye, Biao Yang, Cheng-Jian Lin, Hui-Ming Jia, Jian-Ling Lou, Xiao-Fei Yang, T. Baba, Qi-Te Li, Yu-Cheng Ge, Zhi-Huan Li, Hui Hua, Jin-Yan Xu, Zai-Hong Yang, Jun Feng, Hong-Liang Zang, Qiang Liu, Wei Jiang, Yang Liu, Jing-Jing Li, Wei Liu, Shi-Wei Bai, Jie Chen, Jia-Xing Han, Jia-Hao Chen, Kai Ma, Dong-Xi Wang, Lei Yang, Nan-Ru Ma, LI-Jie Sun
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Abstract:
A multi-nucleon transfer and cluster decay experiment, \begin{document}$^7$\end{document}Li(\begin{document}$^{11}$\end{document}B,\begin{document}$^{14}$\end{document}C\begin{document}$^*\rightarrow\alpha$\end{document}+\begin{document}$^{10}$\end{document}Be)\begin{document}$\alpha$\end{document}, was carried out at an incident beam energy of 55 MeV. This reaction channel has an extremely large Q-value which favors populating the high lying resonant states in \begin{document}$^{14}$\end{document}C. The decay paths from these resonances to various states of the final nucleus \begin{document}$^{10}$\end{document}Be can be selected owing to the experimentally achieved good resolution of the Q-value spectrum. A number of resonant states are reconstructed from the forward emitting \begin{document}$^{10}$\end{document}Be + \begin{document}$\alpha$\end{document} fragments and their major molecular structures can be recognized according to the selective decay paths and the relative decay widths. A state at 22.4(2) MeV confirms the previously measured and theoretically predicted band head of the positive-parity \begin{document}$\sigma$\end{document}-bond linear-chain molecular band. Two additional resonances at 22.9(2) MeV and 24.2(2) MeV are identified and consistent with the predicted \begin{document}$2^+$\end{document} and \begin{document}$4^+$\end{document} members of the same molecular band, providing new evidences for the existence of the exotic clustering chain structure in neutron-rich carbon isotopes. Some higher energy resonances were observed which feature also the \begin{document}$\sigma$\end{document}-bond molecular structure, but further studies are still needed to clarify their ascription in band systematics.
Impact of lepton pT threshold on the charge asymmetry predictions for the inclusive W boson production in pp collisions at 13 TeV
Kadir Ocalan
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This paper presents the impact of lepton transverse momentum \begin{document}$p^{l}_{T}$\end{document} threshold on the \begin{document}$W$\end{document} boson charge asymmetry predictions in perturbative QCD for the inclusive \begin{document}$W^{\pm}+X \rightarrow l^{\pm} \nu +X$\end{document} production in proton-proton (\begin{document}$pp$\end{document}) collisions. The predictions are obtained with various low-\begin{document}$p^{l}_{T}$\end{document} thresholds \begin{document}$p^{l}_{T} >$\end{document} 20, 25, 30, and 40 GeV in a fiducial region encompassing both central and forward detector acceptances in terms of the lepton pseudorapidty \begin{document}$0 \leq \eta_{l} \leq 4.5$\end{document}. The predicted distributions for the lepton charge asymmetry, which is defined by means of the \begin{document}$\eta_{l}$\end{document} (\begin{document}$A_{\eta_{l}}$\end{document}), at next-to-next-to-leading order (NNLO) accuracy are compared with the CMS and LHCb data at 8 TeV center-of-mass collision energy. The 8 TeV predictions are observed to reproduce the data fairly well within the quoted uncertainties. The predictions from the CT14 parton distribution function (PDF) model provide slightly better agreement with the data over the other PDF sets that are being tested. The 13 TeV predictions by using various \begin{document}$p^{l}_{T}$\end{document} thresholds are reported for the \begin{document}$A_{\eta_{l}}$\end{document} and also the charge asymmetries that are defined in terms of the differential cross sections in bins of the \begin{document}$W$\end{document} boson rapidity \begin{document}$y_{W}$\end{document} (\begin{document}$A_{y_{W}}$\end{document}) and transverse momentum \begin{document}$p^{W}_{T}$\end{document} (\begin{document}$A_{p^{W}_{T}}$\end{document}). The NNLO predictions for the \begin{document}$A_{\eta_{l}}$\end{document}, \begin{document}$A_{y_{W}}$\end{document}, and \begin{document}$A_{p^{W}_{T}}$\end{document} distributions are assessed to be in close correlation with the \begin{document}$p^{l}_{T}$\end{document} value. The \begin{document}$A_{\eta_{l}}$\end{document} and \begin{document}$A_{y_{W}}$\end{document} distributions are particularly shown to be more correlated at a higher \begin{document}$p^{l}_{T}$\end{document} threshold. The \begin{document}$A_{p^{W}_{T}}$\end{document} distributions are also reported from the merged predictions with improved accuracy by the inclusion of next-to-next-to-next-to-leading logarithm (N3LL) corrections, i.e., at NNLO+N3LL. The predicted distributions from various \begin{document}$p^{l}_{T}$\end{document} thresholds represent also a finer probe in terms of the capability to provide more constraints on the ratio of \begin{document}$u$\end{document} and \begin{document}$d$\end{document} quark distribution functions in the parton momentum fraction range \begin{document}$10^{-4} < x < 1$\end{document}.
Performance of LHAASO-WCDA and Observation of the Crab Nebula as a Standard Candle
F. Aharonian, Q. An, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, , D. della Volpe, B. D'Ettorre Piazzoli, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B.B. Li, C. Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Li
Published:  
Abstract:
The first Water Cherenkov detector of the LHAASO experiment (WCDA-1) has been operating since April, 2019. The first 10 months of data have been analyzed to test its performance by observing the Crab Nebula as a standard candle. The WCDA-1 achieves the sensitivity of 65 mCU per year with a statistical threshold of 5 \begin{document}$\sigma$\end{document}. In order to do so, 97.7% cosmic-ray background rejection rate around 1 TeV and 99.8% around 6 TeV with an approximately photon acceptance about 50% is achieved after applying an algorithm to separate gamma-induced showers. The angular resolution is measured using the Crab Nebula as a point source to be about 0.45° at 1 TeV and better than 0.2° above 6 TeV with the pointing accuracy better than 0.05°. These values are all matching the design specifications. The energy resolution is found to be 33% for gamma rays around 6 TeV. The spectral energy distribution of the Crab Nebula in the range from 500 GeV and 15.8 TeV is measured and in agreement with results of other TeV gamma ray observatories.
Universal time delay in static spherically symmetric spacetimes for null and timelike signals
Haotian Liu, Junji Jia
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A perturbative method to compute the total travel time of both null and lightlike rays in arbitrary static spherically symmetric spacetimes in the weak field limit is proposed. The resultant total time takes a quasi-series form of the impact parameter. The coefficient of this series at a certain order n is shown to be determined by the asymptotic expansion of the metric functions to the order \begin{document}$ n+1 $\end{document}. To the leading order(s), the time delay, as well as the difference between the time delays of two kinds of relativistic signals, is then shown to take a universal form for all SSS spacetimes. This universal form depends on the mass M and a post-Newtonian parameter \begin{document}$ \gamma $\end{document} of the spacetime. The analytical result is numerically verified using the central black hole of M87 as the gravitational lensing center.
A Bayesian-based Approach for Extracting the Pion Charge Radius from Electron-electron Scattering Data
Alam A Hidayat, Bens Pardamean
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In this paper, we utilize a potentially versatile Bayesian parameter approach to compute the value of the pion charge radius and quantify its uncertainty from several experimental \begin{document}$ e^{+}e^{-}$\end{document} data sets for the pion vector form factor. We employ dispersion relations to model the pion vector form factor for the extraction of the radius. Nested model selection is used to determine the order of polynomial appearing in the form factor formulation that can be supported by the data, adapting the computation of Bayes evidence and Bayesian effective complexity following Occam's razor. Our findings show that five out of six used data sets favor the nine-parameter model for the radius extraction and we average the radii from the data sets based upon this. Despite of some inconsistencies with the most updated radius values, our approach may serve as a more intuitive way to deal with parameter estimations in dispersion theory.
Heavy Ion Induced Charge Exchange Reactions: a Preliminary Study within the Constrained Molecular Dynamics Model
Gianluca Giuliani
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We present a preliminary study of charge exchange heavy ion induced reactions based on the Constrained Molecular Dynamics (CoMD) model. The purpose is to test the capability of the model to predict the occurrence of Single Charge Exchange (SCE) and Double Charge Exchange (DCE) exit channels for three different entrance channels at the same laboratory incident energy. The nuclear reaction dynamics and the nuclear interaction within the CoMD approach are the only ingredients which have given, at this stage, promising results for SCE and DCE cross section calculations. The obtained results suggest the upgrade and the future employment of the model for studies relating the production of exotic nuclei through charge exchange reactions or DCE reactions and their connection with neutrinoless double beta decay.
High Spin States in 71Ga
Jian Zhong, Li-Tao Deng, Shi-Peng Hu, Xiao-Guang Wu, P. C. Srivastava, A. Saxena, Guang-Sheng Li, Yun Zheng, Cong-Bo Li, Qi-Ming Chen, Chuang-Ye He, Wen-Kui Zhou, Bao-Ji Zhu, Qi-Wen Fang, Hui Hua, Jun-Jie Sun, Hui-Bin Sun, Lin Gan, Hai-Ge Zhao, Qi Luo, Zheng-Xin Wu
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Abstract:
Excited states in the odd-A nucleus 71Ga have been studied via the 70Zn(7Li, \begin{document}$ \alpha2n $\end{document})71Ga fusion-evaporation reaction with incident beam energies of 30 and 35 MeV. The level scheme is established up to spin \begin{document}$ I^{\pi} $\end{document} = (29/2+) and excitation energy \begin{document}$ \sim $\end{document} 6.6 MeV. A previously known sequence built on the 9/2+ state is extended as a new rotational band originating from the \begin{document}$ \nu (g_{9/2}^2) $\end{document} alignment. Additionally, negative-parity sequence is also reported. The observed energy levels of 71Ga have been interpreted in the framework of nuclear shell model (SM).
Isospin effects of projectile fragmentation in a Boltzmann-Langevin approach
Bing Li, Na Tang, Feng-Shou Zhang
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The isospin effects of the projectile fragmentation at intermediate energy are investigated using an isospin-dependent Boltzmann-Langevin model. The collisions of mass-symmetric reactions 58Fe, 58Ni + 58Fe, 58Ni at intermediate energies from 30 to 100 MeV/A are studied with different symmetry energies. Yield ratios of isotopic, isobaric and isotonic pairs of fragments from the intermediate-mass region using three symmetry energies are extracted as a function of the N/Z of the composite systems in the entrance channel and the incident energies. It is found that the yield ratios are sensitive to symmetry energies, especially for the neutron-rich systems, and the calculations using soft symmetry energy are closer to the experimental data. The isospin effect is stronger in the soft symmetry energy due to the competition of repulsive Coulomb force and symmetry energy attractive force to the proton. For the first time, the splits are presented, revealing a transition from isospin equilibrium at lower energies to translucency at intermediate energies. The results show a degree of transparency in that the intermediate mass fragments undergo a transition from dependence on the composite systems in the entrance channel to reliance on the projectile and target nuclei.
Erratum and Addendum
Erratum: Covariant Spin Kinetic Theory I: Collisionless Limit, [ Y.-C. Liu, K. Mameda, and X.-G. Huang, Chin. Phys. C 44, 094101 (2020)]
Yu-Chen Liu, Kazuya Mameda, Xu-Guang Huang
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Abstract: